Not only do those pollutants cause short-term problems like smog but they also add to the wider problem of global warming. Last week, the Intergovernmental Panel on Climate Change (IPCC) warned that without tackling our current levels of fossil fuel consumption we could see a global temperature rise of 4 to 5C by 2100 compared to pre-industrial levels. Such an increase could pose catastrophic risks to the planet, including sea level rises, water and food shortages and an increase in extreme weather events.

But this isn’t anything we didn’t know before. For at least a quarter of a century, the world’s brightest minds have been telling us that anthropogenic global warming (i.e. caused by humans) is one of the biggest threats to our future well-being. Tthe IPCC report, funded by the United Nations and put together by more than 1,250 experts in the field, was first released way back in 1990 – the year Nelson Mandela was released from prison, Margaret Thatcher resigned from office and MC Hammer hit the charts in those parachute pants.

Despite years of inaction from governments and big industry, the good news is that it’s not too late to repair, or at least limit, the damage. And with an estimated 42 per cent of Britain’s carbon emissions being a direct result of individuals’ actions, each and every one of us has the opportunity to make a difference. Instead of relying on policymakers to take responsibility, there is one organisation changing the world one small pledge at a time.

The DoNation is a website that encourages people to donate by doing, as opposed to giving cash. People running a marathon or climbing a mountain can raise sponsorship by asking their friends and family to pledge small actions like eating less red meat or doing their washing at a lower temperature. The website then helps to calculate the resulting carbon savings.

It started in 2009 when The DoNation founder, Hermione Taylor, then a Masters student in environmental technology, embarked on a cycle trip to Morocco.

‘Partly because it was the beginning of the credit crunch, my friends were all students, there wasn’t a lot of money going around and people were getting a bit tired with endless sponsorship requests,’ she told Metro.

‘But I realised the environment didn’t need people’s money as much as it needed their action. The very people that were able to give most generously financially were then jumping into their 4x4s or leaving all the lights on at home. They could actually do more meaningful actions without giving money.’

So after convincing 216 friends and family to ‘do’ pledges, Taylor’s trip ended up saving the equivalent carbon dioxide as 84 flights from London to Morocco. It suddenly became clear that a small collection of ‘doers’ could join together to make a very big impact.

But not only do these actions, like eating more seasonal food or cycling to work, have benefits on the environment – they have also saved money and made people fitter.

‘One girl in our office started walking up the stairs every day, on the Tube and when she got to work,’ said Not only was she saving on electricity but after a couple of months she’d managed to shed nearly half a stone,’ explained Taylor.

Every day in Britain, it is estimated that 30m litres of excess water are boiled in kettles only for them to go cold again. So only boiling the water you need for your cuppa will help to ease the burden on water supplies, reduce electricity use and in turn reduce your monthly energy bill – likewise with spending less time in the shower each morning. Plus you could even have a few more precious minutes in bed.

So not only are these pledges good for converted environmentalists but they have other obvious benefits for those who are (still) sceptical about climate change.

‘Most often people actually carry on doing their pledge in the long-term because it just makes sense for their personal benefit,’ said Taylor.

For those raising sponsorship, the campaign itself can be just as rewarding as raising money. Alan Hayes completed his first London Marathon this month, in an impressive 3hrs 4mins, and raised 53 pledges on his DoNation page, totalling 2,423kg of CO2 saving.

‘It has an unintended disruptive quality to it, because once you start to get people’s attention you start to engage them in a dialogue and you start to change their thinking and behaviour,’ he said. ‘It’s easy to raise money. I’ve had people speak to me and write to me and say, this is great but can I just give you some cash.’

For Hayes, who has previously raised DoNation pledges for his Movember effort in 2012 and an ultra-marathon, the idea is about changing people’s long-term habits to really make a difference.

‘Cash is something easy and disposable and most people can afford a tenner or a fiver if you ask them nicely, but this challenges their own status quo and gets them out of their comfort zone,’ he said.

It’s not about making huge lifestyle changes; most of the pledges are small actions like turning the heating down a couple of degrees or eating more sustainably-sourced fish.

‘They become part of life and lifestyle – all the pledges are easy to do, they just require a bit of thought and effort initially,’ said Hayes. ‘They cause very little trouble once you actually start doing them.

‘I fail to see how I would switch to raising funds again. I want to make a real difference and impact by raising people’s awareness in changing the things they do every day.’

Since its launch, The DoNation has calculated that its small community of 4,600 doers has saved more than 206 tonnes of CO2 from doing eight-week pledges. That is the equivalent of 417 flights from London to New York or driving around the world 21 times. But with four out of five of those pledges estimated to turn into long-term habits, there is a potential carbon saving of 1,042 tonnes each year.

Taylor’s believes those planning on running next year’s London Marathon, for which the ballot opens today, should ask people to make change instead of asking for a handful of change.

‘The most important thing people can do is just to take really small, simple actions,’ she said.